Building A better Hot Air Intake (+70-100F) ???

Rick Reece · 02-12-2005, 06:41 PM

After reading about John's use of a F-150 heat shield and getting a +45 degree temp increase I figured I could improve my simple dryer hose. During the Christmas Holidays I put my Insight up on Jack stands and looked at how I might improve the hot air intake. I decided that if I could get +20F from one catalytic converter using both would be even better. Since the exhaust seams to travel down the length of the car in a bit a cavity I figured I could block this off to outside air. Since the length of the intake was fairly long I figured I would put a bit of a scoop to push the air up to the airbox. THe intake consists of several pieces.

1. My 2inch plumbing elbow connected to the air box
2. A 4in dryer vent aluminum crimped over the 2inch elbow
3. A temperature probe inserted into the dryer vent at the connection of the above two items

Picture shows the above items
http://webpages.charter.net/r1957/Flipper/airbox.JPG

4. I used reflectex and aluminum duct tape to create a enclosed area surrounding the catalytic converter. This area connects to the cavity under the car moving back toward the exhaust resonator.

http://webpages.charter.net/r1957/Flipper/frontview.JPG
http://webpages.charter.net/r1957/Fl...engineview.JPG

5. Lastly I used a home heating vent to create the air scoop.
http://webpages.charter.net/r1957/Flipper/airintake.JPG

I have had this on my car for about 5K miles and it seams to be holding up well. The lowest gain in temp I have seen is +70F but if I am in traffic or crusinging around town slow then 100F will be seen. The normal highway gain is 70-80F with uphill runs heating the temp occasionally to 90F. The gains in fuel economy are noticable but certainly not at summer levels (Guess the cold winter blend fuel) keeps a lid on how much the air temp can help with the mpg. Another advantage is that even in freezing weather the car warms up much quicker making autostop available. On the downside the scoop will scoop snow which I learned the hard way. Fortunately I didn't have to drive through very deep snow for long.

I have used a OBDII scan tool and the intake temp is usually a 5-10F below my temp sensor value. I suspect this is because the sensor is in the aluminum vent and is getting conducted heat from the metal. I have also noted that the oil temp is reading a bit high (180-190 range) and lastly the water temp stays around 197-199F.

I plan to leave it in this configuaration until mid to late spring but Robert had an excellent idea about wrapping springs around the catalytic converter. This would conduct the heat and provide a larger surface area for the heat transfer to the air. I think I may try this route next winter. Have fun, Rick

b1shmu63 · 02-13-2005, 01:44 AM

Nice project Rick.

I converted the three panels under the engine into a single fiberglass plate myself. It looks like you have done something similar but have used an insulating and reflecting material and have included a fresh air scoop at the back. Pehaps I can just use some of that insulation and attach it to my plate.

Is the scoop is really necesary or effective? Wouldn't it create air turbulence and resistance? I could not use something like that myself because of the roads I drive on. Grass, stones and snow would certainly rip it off! I have installed a radiator block as well but have not done anything with the air intake. I was hoping to make something with a stainless steel sheet and a little silver soldering. Perhaps this summer.

Rick Reece · 02-13-2005, 08:26 AM

I don't think the scoop is all that necessary and yes it probably increases drag. I may cut it off in a week or two and see how just the enclosed area works. The only reason I put the scoop is that I was worried that the air flow next to the opening would work to pull air out making it hard for the engine to get enough air. Have fun, RIck

Insightful Trekker · 02-13-2005, 09:34 AM

So your seeing a 70 to 100F increase over ambient?

WOW

The best arctic <g> hot air mod yet

FYI I think your BBcode url's are backwards the /url is the closing one and they don't display as links. A few minutes with some photo editing software to crop and compress the images would also be helpful. Not to sound ungrateful but the lighting and focus makes interpreting several of these pics difficult.

I'd be wary of IAT's in the 150F range, if that's what your system capable of. (ambient 50F +100F gain). Some of the plastic air box parts are likely to begin softening in that range.

Rick Reece · 02-13-2005, 08:50 PM

John,
Thanks I fixed the links. I also took a look at the pictures. They are very clear on my computer at home but from here (I'm in DC now) they don't look very good. As you can see I am not very efficient at posting these things. The 100F gain was noticed driving around town. I mostly cruise on the Interstate where the 70-80 range is common. The temp today got up to 138 for the intake for a high. I'll have to pull over and check the air box next time I have a really high reading. Have fun, RIck

tubesguy · 10-22-2005, 12:20 PM

Are these pics available anymore? It's getting a little cool here in Wisconsin, and I may have to get going on a hot air intake mod. Thanks - Pat

Insightful Trekker · 10-22-2005, 12:39 PM

Don't think Rick is going to pursue this mod. It appears that 100-110F IAT (Intake Air Temperature) is the maximum range a hot air "mod" has an MPG effect. So +100F over ambient is wayyy too much for all but "arctic" conditions

And his +100F mod had some underbody "problems" in regard to road hazard damage.

JoeCVT (

) had a similar mod to mine (see the url in my sig) and AFAK remember posted with pics in a ooold thread. Either of ours won't be as effective during the coldest part of what a Wisconsin winter can dish out, but better than nothing

HTH!

Rick Reece · 10-22-2005, 03:39 PM

Sorry I deleted the pictures. I expect to put my hot air mod back in soon so I will take some pictures when I do. This time I think I will leave the scoop off. The goal is to have a intake temp in the 100-110 range so that you quickly get autostop in cold weather and it helps some with lean burn although the mpg numbers are not as high as a regular summer. Have fun, Rick

tubesguy · 10-22-2005, 05:20 PM

Thanks guys

nortoncomando · 10-24-2005, 09:52 AM

Small note on auto-stop: I think it looks at the outside air temp sensor (> 41 deg. F for auto stop) located aft of grill and forward of radiator. Mine was disconnected when I bought the car used and never got an auto-stop until I reconnected it.
Also, that trick with the climate control showing all the temp. read-outs in the car ( including intake air temp ) would be usefull in the set-up of this mod. Looking forward to new pics of mod.